A communication system, such as a Long Term Evolution (LTE, Long Term Evolution) system, can support a time division duplexing (TDD, Time Division Duplexing) scheme. That is to say, an uplink (UL, Uplink) and a downlink (DL, Downlink) may use different timeslots of a same frequency. An LTE TDD system may configure an uplink-downlink configuration (Uplink-Downlink Configuration) in a semi-static manner according to a service type, so as to satisfy a requirement of different uplink-downlink asymmetrical services.
Currently, the LTE TDD system defines a total of seven uplink-downlink configurations. Referring to Table 1, “D” denotes a downlink subframe, “U” denotes an uplink subframe, and “S” denotes a special subframe. As can be seen from Table 1, time-domain resources reserved for a downlink service in uplink-downlink configuration manners account for 40% to 90%. In the LTE TDD system, an uplink-downlink configuration in use is configured in a semi-static manner, where uplink-downlink configuration indication information is carried in a system information block 1 (SIB1, System Information Block-1) of a system broadcast message. The SIB1 has a transmission period of 80 ms (milliseconds), and is repeated every 20 ms within each transmission period thereof, so as to ensure correct reception for all users in a cell.
TABLE 1Uplink-Downlink-downlinkto-Uplinkconfigura-Switch-pointSubframe number (Subframe number)tion.periodicity012345678905 msDSUUUDSUUU15 msDSUUDDSUUD25 msDSUDDDSUDD310 ms DSUUUDDDDD410 ms DSUUDDDDDD510 ms DSUDDDDDDD65 msDSUUUDSUUD
Because an existing SIB1 normally changes slowly, in order to avoid energy consumption caused by a UE reading the same SIB1 repeatedly, the system further defines a message change period of the SIB1. Information in the SIB1 is changed and sent to a UE only at a start moment of one change period, and the information in the SIB1 remains unchanged within one change period. A UE in a connected state needs to update the SIB1 only at a start moment of a change period. Regarding a UE in an idle state, if a change occurs on an SIB1, an existing base station notifies the UE in the idle state by paging, and the UE in the idle state wakes up and receives a new SIB1 at a start moment of a next change period. The SIB1 has a minimum change period of 640 ms and a maximum one of about 41 s (seconds).
In order to avoid uplink-downlink interference between cells, in a conventional TDD system, normally multiple cells within a large range all use a same uplink-downlink configuration which remains unchanged for a long time. A change in the uplink-downlink configuration, if necessary, is made to the multiple cells together, and a hard handover is performed by interrupting data transmission. However, in an isolated cell or a cell covered by a low-power node, an interference impact between cells is insignificant, and in cases where the cell serves a small number of users, a condition of an uplink-downlink service burst occurs obviously. A technical problem worth studying in such scenarios is how to use a frequency spectrum resource more efficiently to take specific advantages of a TDD system.